The findings, in a study by the Weizmann Institute of Science and Wolfson Hospital near Tel Aviv on the role tears play in non-verbal communication, suggest that a chemical in women’s tears lowers men’s testosterone levels.

Looking beyond any impact on sexual drive, the researchers hope their findings might one day be used in cancer treatment.

“There are a number of illnesses that are treated by lowering the levels of testosterone, the most prominent is prostate cancer,” said Professor Noam Sobel of the Weizmann Institute.

He said the current methods of testosterone reduction cause side effects, and his research team hoped that the use of tears could eliminate them.

Men who took part in the study, published in Science Express, were asked to sniff the tears of women who had cried while watching sad films.

Sobel said researchers had expected the tears would boost the men’s sense of empathy. Instead, their heart and respiratory rates, salivary testosterone and a brain scan all pointed to a reduction of sexual arousal.

The chemo-signal in women’s tears, he said, was one way of saying “no, I am not interested.”

“Communication is key to survival. Humans, like all mammals, use smell in their communication. It is very efficient if you have a chemical signal which transmits what you want — or clearly don’t want — in a sexual situation,” Sobel added.

He said the researchers had set out to study the tears of both men and women, but only one man had responded to a notice put up on Israeli college campuses asking for volunteers who thought they could cry easily.